And I'm Renee Montagne. U.S. Special Forces are headed back to Iraq. President Obama announced yesterday he's sending up to 300 of them as military advisers to Iraq to gather intelligence and work with security forces. This in response to the rapid takeover of several Iraqi cities by the Islamic militant group ISIS. As NPR White House correspondent Tamara Keith reports, this is the legacy of a war that most assumed was in the history books.

TAMARA KEITH, BYLINE: U.S. military involvement in Iraq officially ended as the clock wound down on 2011 and the last of the troops pulled out. But it seems that wasn't really the end. The radical group Islamic State of Iraq and Syria has swept into the country taking control of cities and blazing a path toward Baghdad. Given the U.S. history in Iraq and the risk that an explosion of sectarian violence there could destabilize the whole region. President Obama said something has to be done.

(SOUNDBITE OF ARCHIVED RECORDING)

PRESIDENT BARACK OBAMA: We have humanitarian interests in preventing bloodshed. We have strategic interests in stability in the region. We have counterterrorism interests. All those have to be addressed.

KEITH: But for a number of reasons, what the president announced yesterday is limited. In the White House briefing room, Obama described the mission of the military advisors he's sending in.

(SOUNDBITE OF ARCHIVED RECORDING)

OBAMA: Some of the best people on the ground doing assessments of what exactly the situation is, starting, by the way, with the perimeter around Baghdad and making sure that that's not overrun. That's a good investment for us to make, but that - that does not foreshadow a larger commitment of troops to actually fight in Iraq. That would not be effective.

KEITH: He is adamant there will be no American combat operations on the ground in Iraq.

(SOUNDBITE OF ARCHIVED RECORDING)

OBAMA: We do not have the ability to simply solve this problem by sending in tens of thousands of troops and committing the kinds of blood and treasure that has already been expended in Iraq. Ultimately this is something that is going to have to be solved by the Iraqis.

KEITH: How? Obama says a political solution is needed. Problem is Iraqi politics are a mess. The country's prime minister Nouri al-Maliki, is Shiite, and his policies have been hostile to Sunnis. The radical group ISIS capitalized on those sectarian divisions, easing their way into Sunni-dominated cities. President Obama wouldn't say whether he thinks Maliki needs to go, but he is calling for a unity government.

(SOUNDBITE OF ARCHIVED RECORDING)

OBAMA: Shia, Sunni, Kurds, all Iraqis must have confidence that they can advance their interests and aspirations through the political process rather than through violence. National unity meetings have to go forward to build consensus across Iraq's different communities.

KEITH: There is skepticism about whether this kind of unity is possible or really a solution, in the halls of Congress and well beyond. Republican Senators John McCain and Lindsey Graham said in a statement the president can't wait for the political process to, quote, "help Iraqis arrest their country's descent into chaos." As Stephen Biddle sees it, Iraq is already in the midst of a civil war. Biddle is a professor of international affairs at George Washington University.

STEPHEN BIDDLE: You're necessarily confronting a series of bad options and looking for the least bad.

KEITH: He says what's happening today is a predictable outcome of the full troop withdrawal of 2011. President Obama defended that moved saying it was a decision of the Iraqi government and Prime Minister Maliki. Biddle says now there's only so much the U.S. can do.

BIDDLE: Ethno-sectarian civil warfare is kind of like toothpaste in the tube. Once it gets out of the tube, it's very hard to put back in.

KEITH: And Biddle says it's out.

BIDDLE: And sure enough, it's now going to be very hard to get it back in.

KEITH: Biddle says all the U.S. can hope to do is shorten what he figures will be a lengthy sectarian conflict and maybe help prevent it from spreading to other countries. Tamara Keith, NPR News, the White House. Transcript provided by NPR, Copyright NPR.